Molecular Cell
Volume 33, Issue 3, 13 February 2009, Pages 299-311
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Article
Fission Yeast Scm3: A CENP-A Receptor Required for Integrity of Subkinetochore Chromatin

https://doi.org/10.1016/j.molcel.2009.01.019Get rights and content
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Summary

The mechanisms ensuring specific incorporation of CENP-A at centromeres are poorly understood. Mis16 and Mis18 are required for CENP-A localization at centromeres and form a complex that is conserved from fission yeast to human. Fission yeast sim1 mutants that alleviate kinetochore domain silencing are defective in Scm3Sp, the ortholog of budding yeast Scm3Sc. Scm3Sp depends on Mis16/18 for its centromere localization and like them is recruited to centromeres in late anaphase. Importantly, Scm3Sp coaffinity purifies with CENP-ACnp1 and associates with CENP-ACnp1 in vitro, yet localizes independently of intact CENP-ACnp1 chromatin and is differentially released from chromatin. While Scm3Sc has been proposed to form a unique hexameric nucleosome with CENP-ACse4 and histone H4 at budding yeast point centromeres, we favor a model in which Scm3Sp acts as a CENP-ACnp1 receptor/assembly factor, cooperating with Mis16 and Mis18 to receive CENP-ACnp1 from the Sim3 escort and mediate assembly of CENP-ACnp1 into subkinetochore chromatin.

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4

These authors contributed equally to this work

5

Present address: Lincoln University, Canterbury 7647, New Zealand

6

Present address: Departamento de Genética, Universidad de Malaga, 29010 Malaga, Spain